#include <iostream>
#include <cstdlib>
#include <unistd.h>
#include <strings.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>

using namespace std;

void Usage(std::string proc)
{
  std::cout << "\n\rUsage: " << proc << " serverip serverport\n"
            << std::endl;
}

// ./udpclient serverip serverport
int main(int argc, char *argv[])
{
  if (argc != 3)
  {
    Usage(argv[0]);
    exit(0);
  }
  std::string serverip = argv[1];
  uint16_t serverport = std::stoi(argv[2]);

  struct sockaddr_in server;
  bzero(&server, sizeof(server));
  server.sin_family = AF_INET;
  server.sin_port = htons(serverport); //?
  server.sin_addr.s_addr = inet_addr(serverip.c_str());
  socklen_t len = sizeof(server);

  int sockfd = socket(AF_INET, SOCK_DGRAM, 0);
  if (sockfd < 0)
  {
    cout << "socker error" << endl;
    return 1;
  }

  // client 要bind吗？要！只不过不需要用户显示的bind！一般有OS自由随机选择！
  // 一个端口号只能被一个进程bind，对server是如此，对于client，也是如此！
  // 其实client的port是多少，其实不重要，只要能保证主机上的唯一性就可以！
  // 系统什么时候给我bind呢？首次发送数据的时候

  string message;
  char buffer[1024];
  while (true)
  {
    cout << "Please Enter@ ";
    getline(cin, message);

    // std::cout << message << std::endl;
    // 1. 数据 2. 给谁发
    sendto(sockfd, message.c_str(), message.size(), 0, (struct sockaddr *)&server, len);

    struct sockaddr_in temp;
    socklen_t len = sizeof(temp);

    ssize_t s = recvfrom(sockfd, buffer, 1023, 0, (struct sockaddr *)&temp, &len);
    if (s > 0)
    {
      buffer[s] = 0;
      cout << buffer << endl;
    }
  }

  close(sockfd);
  return 0;
}